Revenue Recognition - Summary Disaggregation of Revenue by Region (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Jan. 31, 2020	Oct. 31, 2019	Jul. 31, 2019	Apr. 30, 2019	Jan. 31, 2019	Oct. 31, 2018	Jul. 31, 2018	Apr. 30, 2018	Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2018
Disaggregation of Revenue [Line Items]
Revenue	$ 188,251	$ 166,593	$ 145,826	$ 121,988	$ 105,800	$ 90,121	$ 74,526	$ 60,070	$ 622,658	$ 330,517	$ 151,478
Revenue from Contract with Customer | Geographic Concentration Risk
Disaggregation of Revenue [Line Items]
Percentage of Revenue									100.00%	100.00%	100.00%
Americas
Disaggregation of Revenue [Line Items]
Revenue									$ 500,622	$ 270,132	$ 125,428
Americas | Revenue from Contract with Customer | Geographic Concentration Risk
Disaggregation of Revenue [Line Items]
Percentage of Revenue									81.00%	82.00%	83.00%
APAC
Disaggregation of Revenue [Line Items]
Revenue									$ 51,152	$ 27,720	$ 13,652
APAC | Revenue from Contract with Customer | Geographic Concentration Risk
Disaggregation of Revenue [Line Items]
Percentage of Revenue									8.00%	8.00%	9.00%
EMEA
Disaggregation of Revenue [Line Items]
Revenue									$ 70,884	$ 32,665	$ 12,398
EMEA | Revenue from Contract with Customer | Geographic Concentration Risk
Disaggregation of Revenue [Line Items]
Percentage of Revenue									11.00%	10.00%	8.00%